Similar experience... Although, I used it more for 'eyecatchers'; it's hard a gauge the effect of those. Depending on how 'local' you are, ads on the back of a bus might be more effective. - But then, it does work for some people; specialist retail perhaps?

If I could find a PPC strategy which produced a decent return on investment I would have no problems ploughing money into this. If for example everyone hundred pounds you invested resulted in a profit of £150, surely it’s a no-brainer. These are the kind of margins I would need to make a PPC strategy attractive.

From your experience @Matt Quinn , which advertising mediums offer the best returns? I appreciate this is difficult to answer because there are so many different types of business which fit with different types of advertising, but on the whole what would you suggest?

There's no real answer to this... Different things work for different products/services at different times.

My best advice on that score is to consult an advertising/marketing specialist - and by that I mean an agency that creates advertising campaigns as opposed to those who just want to sell you space on a particular platform. - The clue here is that they will be in a position to present a number of different options from independent sources, and will spend time profiling the target audience of your business and guiding the design of your campaign down an appropriate path.

What works brilliantly for selling pop stars to children is likely to grate on many adults. - there really is no 'one size fits all' solution. It's important too that you don't attract the wrong kind of client... i.e. those with unrealistic expectations.